A funnel arrangement is usually employed at the outlet or delivery end of a card machine to bring together or press together a sliver which is delivered by the card machine. The sliver comprises a relatively loose air-including structure which is compressed with simultaneous pressing out of the included air by the funnel arrangement so that the already precompressed fiber band or sliver can be supplied to the nip of the following calender roll pair. Usually, the calender roll pair is a stepped roll pair which detects deviations of the sliver count and the output signal of which can be used to control the card machine.
As in all other areas of yarn manufacture, the aim is to increase the production rate of the card machine and this has also been achieved to a large extent. However, at these high production rates, a problem is encountered in that a sliver moving at high speed contains a relatively large amount of air which is squeezed out of the sliver in the funnel. However, the squeezing out of the air at high sliver speeds results in a spreading of the sliver which occurs directly in front of the funnel. Such spreading of the sliver can be to such an extent that the sliver expands balloon-like beyond the edges of the inlet end of the funnel and this can lead to damaging the fibers, to yarn faults and possibly to an interruption in the sliver. Furthermore, the initial introduction of the sliver through the nozzle opening of the funnel requires a certain amount of skill.